Friday, December 6, 2013

What was the first road car to use limited-slip differential?

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nakkecil22


I know Ferdinand Porsche used it on a GP car in 1932, but did he use it in the early 356? Or the early 911? Because I found that the Facel Vega HK500 had LSD.

I've wondered now, all of a sudden, since I thought LSD was new.



Answer
The main reason why manufacturers, to this day, have poured millions into auto racing is that it really is a testing ground for the production car industry; quantum leaps such as disc brakes would have taken decades more to hit the streets if Jaguar had not evaluated them on it's successful C-Type race car.

Getting power from the engine to the wheels of an automobile has provided a seemingly endless challenge for rear-wheel-drive, front-wheel-drive, 4-wheel-drive, front-engine, rear-engine, and mid-engine cars, longitudinal, transverse, vertical, slant, and flat engines, plus an amazing array of hardware in between. George Selden's notorious 1877 patent was for a front-drive carriage with a transverse 3-cylinder engine, anticipating the Chevy/Suzuki Sprint by over a century. When it comes to car designs, there are very few new ideas, just progressively successful adaptations of old concepts.

The heart of the drivetrain is the transmission. Because gasoline engines develop their torque over a very narrow speed range, several gears are needed to reach useful road speeds. (Steam engines and electric motors can be used in cars with no transmissions.)

The modern transmission was introduced by a pair of Frenchmen -- Louis-Rene Panhard and Emile Levassor -- in 1894. The engineers had invited the press to a demonstration of "the most revolutionary advancement to date in the brief history of the motor car industry." Unfortunately, the engine in their demo vehicle died, and they were reduced to giving a chalk talk on multi-geared transmission theory to a bored press corps.

One 19th-century newsman reported their invention as "more hocus-pocus from charlatans trying to cash in on the public's fascination with the new motor car." Maybe the inventors should have skipped the tech talk and just used the description later attributed to Panhard: "It's brutal, but it works!"

Cars of the time transmitted engine power to the wheels in a simple fashion that was easy for non-engineers to visualize. The engine drove a set of bevel reduction gears that drove a shaft and pulley. Leather belts extended between the pulley and geared wheels on an axle. One wheel, the small one, got the car going by meshing with a ring gear on one of the driving wheels. The big wheel then took over to get the car to hustle along at a top speed of 20 mph. If the car encountered a hill that it did not have the power to climb, the driver would come to a dead stop so he could engage the small wheel.

Thus did British auto pioneer F. W. Lanchester describe the transmissions in his cars: "One belt-driven HIGH gear that will go over everything and one bel-driven LOW gear in case the car had to climb a tree."

It was not until a year after their disastrous news conference that Panhard and Levassor regained their reputations. At this time, they had their first car ready for the press to drive. With it, they changed a lot of minds.

That 1895 Panhard-Levassor was revolutionary -- not the transmission alone, but the whole drivetrain layout. In fact, it has served as the prototype for most vehicles built in the 90 years since then. Unlike other cars of that day, it possessed a vertically mounted engine in the front of the vehicle that drove the rear wheels through a clutch, 3-speed sliding gear transmission and chain-driven axle. The only modern features missing from the setup were a differential rear axle and driveshaft. These came along three years later, in 1898, when millionaire-turned-auto-hobbyist Louis Renault connected a vertical engine with transmission to a "live" rear axle by means of a metal shaft.

The live rear axle -- which Renault adapted from an idea developed in 1893 by an American, C. E. Duryea -- was called the differential rear axle. It used a number of gears to overcome the problem of rapid tire wear, which resulted on turns with the "dead" axles used by all other carmakers. "Differential" referred to the ability of the unit to turn the outer driving wheel faster than the inner driving wheel, eliminating tire scuffing in turns.

By 1904, the Panhard-Levassor sliding gear manual transmission had been adopted by most carmakers. In one form or another, it has remained in use until recent times. Obviously, there have been improvements, the most significant being the invention of a synchronizing system that permits drive and driven gears to be brought into mesh with each other smoothly without gear clashing. This system allows both sets of gears to reach the same speed before they are engaged. The first of these synchromesh transmissions was introduced by Cadillac in 1928. An improvement to the design patented by Porsche is widely used today.

Between the time the sliding gear-transmission was introduced and the perfection of the synchromesh, there were other attempts at making it easier for the driver to shift gears. One was the planetary transmission in the 1908 Model T Ford. It had a central gear, called the "sun" gea

Is there anything I can do to avoid this rental car damage charge?




Pmpinainte


I think I may be getting the short end of the stick here but I'll wait to see your opinion.

I just returned a rental car after having it for 3 weeks while my car was getting repaired for a serious accident. I got a call this afternoon saying that there were multiple scratches on my rental car about 2 feet in length cutting through the clear coat running from behind the front wheel well to the door. Almost at the bottom of the car.

This was news to me as I did not hit anything while I was driving and I did not notice anything when I returned the car to the repair shop. I am going in to see the damage with my own eyes tomorrow.

I have this feeling that if I look at previous rental contracts before mine(where they mark prior minor scratches/dings) that I would find this one on there. It is so low on the car that I honestly would have missed it when walking around the car when I first was picking it up. Am I able to get a copy of the prior rental agreements from Enterprise? I know they have a damage report but that is only for major damages that need fixes such as damage to bumper or accident damage.

Is there anything I can do? I stopped insurance after 10 days because it was 20 dollars a day and I didn't want to pay anymore. Is there anything that can be done or anyway I can fight this? Anyone know how much a 2 foot scratch costs to repair?

Like I said I'm thinking I might be screwed.
I returned my car to a repair shop who partners with Enterprise. They collect the keys and an Enterprise reps picks up the vehicle Later. No one from Enterprise was there to verify damage.



Answer
If they did not notate the damage when you returned the car, you are not responsible. The damage could have occurred after you returned the car. Tell them that you are not going to pay for damage that was not shown to you when you returned the vehicle, and if they want to sue you you will be happy to file a counter suit for harassment.

They would need to prove that the damage was on the vehicle when it was returned, not that they found it later




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